Same problem as yours and many others as I can see. I called samsung customer support and they told me to change password.I did this and nothing worked cloud would keep on with notification to re sign in .I kept trying with "processing failed " I even emailed tech support for help and was advised to change password .I spent the rest of day trying to figure out what was at the cause of this.I then could see when I expanded notification banner it was coming from "Samsung Experience Service " app. Both this app and cloud had recently been updated .I uninstalled updates for both Samsung Cloud and Samsung Experience Service. When I tried to sign in again it worked and so far has not signed itself out as before. At.present I am using Samsung Experience service 3.0 not the updated 4.0.
I think there is a conflicting bug in either or both of these updated apps.I will not update them for a while in,the hopes samsung patch any errors in these.Hope this helps to you and others with this.
